Multifunctional illumination device

ABSTRACT

In order to improve road safety, modern vehicles are provided with sensor systems, which assist the driver of the vehicle either directly or indirectly with respect to the environment surrounding said vehicle, especially with regard to early recognition of dangerous situations, in addition to the usual illumination device. Said systems more particularly include radar systems for detecting distance and the relative speed of objects or night vision improvement systems which are based on illumination of the field of the road environment with infrared light. According to the invention, the illumination means of the illumination device are formed by an arrangement of a plurality of semiconductor light sources ( 2 ) grouped together to form a field. Sensor elements ( 3 ) are arranged at individual positions of said field instead of said semiconductor sources ( 2 ). A multifunctional headlight can thus be advantageously created. Said headlight can be embodied as a robust, compact, low-space unit. By virtue of the fact that the light sources ( 2 ) and the sensor elements ( 3 ) do not necessarily use the same lens system ( 1 ) i.e. each individual element of the multifunctional headlight can be provided with an individually designed lens system ( 1 ), the beam path of the illumination device can be separated from the field of vision of the sensor system and can thus be determined independently over large areas.

BACKGROUND OF THE INVENTION

1. Field of the invention

The invention relates to a multifunctional illumination device and amethod for operating such a device according to the preambles of patentclaims 1 and 11.

2. Related Art of the Invention

For the purpose of improving safety in road traffic, in addition toconventional illumination equipment modern vehicles have additionalsensor systems, which directly or indirectly support the vehicle driverand are intended for observing the surroundings of the vehicle,particularly with regard to the early detection of dangerous situations.These include, in particular, radar systems for detecting the range andrelative speed of objects, or else night vision improvement systems thatare based on the illumination of the road surroundings with infraredlight. These systems are generally designed as independent systems andare integrated in a spatially separate fashion as additional componentsalongside illumination and signaling systems on the vehicle.

A compact design of ambient sensors and motor vehicle headlamps isdescribed in document DE 196 32 252 A1. Described herein is a vehicleheadlamp that has a housing in common with a sensor device. The headlampis arranged in the housing downstream of a diffusion lens covering thelight exit opening. The sensor device is also likewise arrangeddownstream of the same diffusion lens, the diffusion lens beingspecifically adapted region to the optical requirements of the sensor.

In a similar way, document DE 197 31 754 A1 shows a combination of aconventional motor vehicle headlamp with a distance sensor. Here, thesensor signals are directed via a mirror located in the headlamp suchthat it is possible to make common use of the optical and mechanicalcomponents for beam passage, beam shaping and beam deflection byheadlamp and sensors.

In the case of these combined arrangements of headlamps and sensordevices, it is necessary to arrange the light source and sensor in afashion clearly separate in space in order to avoid reciprocalinfluence. If, nevertheless, the aim is to implement a spatially compactdesign, this is possible only with the aid of delicate mirrorarrangements that can also be severely damaged even in the event oftrivial accidents of no importance occurring in road traffic.

A spatially compact integration of a photodetector of an opticaldistance measurement device in a headlamp is exhibited in JP 06-325296A. The light source of the headlamp and the photodetectors are arrangedin this case offset from one another downstream of a common lens suchthat the beam paths of the two sensors are separated from one anotherand therefore do not influence one another reciprocally. However, thecompact, robust design results here in a restricted variability in thedesign of the possible beam paths.

SUMMARY OF THE INVENTION

Starting from the prior art, it is the object of the invention toprovide a multifunctional illumination device that can be implemented ina compact design and in the case of which the path of radiation of theillumination and sensor device can be freely determined in a very widerange.

The object is achieved by a device and by a method suitable foroperating the device having the features of patent claims 1 and claim11. Advantageous refinements and developments of the invention aredescribed in the dependent claims.

The solution within the scope of the first embodiment of the inventionprovides that the luminous means of the illumination device are formedby an arrangement of a multiplicity of semiconductor light sourcesgrouped to form an array, and that sensor elements are arranged insteadof the semiconductor light sources at individual positions of thisarray. It is thereby possible to provide advantageously amultifunctional headlamp that can be implemented in a robust design as acompact unit in a very small space. Since the light sources and thesensor elements no longer need to necessarily use the same opticalsystem, but each individual element of the multifunctional headlamp canhave an individually fashioned optical system, the beam path of theillumination device can be separated from the field of view of thesensors, and can be fixed independently of one another within wideranges.

The selection of suitable semiconductor light sources is not restrictedhere to those that emit light in the physical wavelength region. Rather,the most varied semiconductor light sources that emit light in differentwavelength regions can conceivably be used. Thus, in particular, it ispossible to conceive an advantageous combination of semiconductor lightsources that emit visible and infrared light.

In the case of semiconductor light sources that emit light in thenonvisible region, in particular, it is conceivable for them to be usedfor different purposes. One of the main objects could be their use assource of illumination within a system for improving visibility, whileanother expedient application resides in their use as transmittingsources in a transceiver arrangement. It is equally conceivable here touse one and the same light source or group of light sources both asillumination source and as transmission source, or else in each case toassign one or the other task (illumination task or transmission task)permanently to specific light sources or groups of light sources.

In the case of use within a transceiver arrangement, the sensor elementsintegrated in the multifunctional headlamp advantageously function asreceivers. However, the receivers could also be located at differentobjects in the surroundings of the multifunctional illumination device;thus, for example, on other vehicles for the purpose of enablingvehicle-to-vehicle communication, or at receiver points of fixedlocation, for example for recording information in conjunction withautomatic road toll systems. This means that with reference to thetransceiving functionality of a multifunctional illumination device thelatter can form a closed unit per se, in which case it is generallynecessary to operate the mutually assigned light source and the sensorelements in a synchronized fashion with one another. However, it is alsopossible, nevertheless, for a pair or a multiplicity of illuminationdevices taken together to form a flexible unit in the case of which thenumber of associated transceiver components changes continuously withtime. In such a flexible configuration, the individual spatiallyseparated communication elements generally work in an asynchronousoperating mode with one another.

In order to implement a design of the multifunctional illuminationdevice that is as compact as possible, the individual optics that areassigned to the semiconductor light sources or the individual sensorsare designed to be as flat as possible and have as small across-sectional surface as possible on the side where they are connectedto the semiconductor light sources or sensors. Thus, it is possible toachieve a packing density of optical and sensor elements thatsimultaneously permits a high radiation density and a high sensorsensitivity. In particular, the radiation density and the sensitivitycan thereby be raised for specific applications when these applicationsare not implemented with the aid of individual elements, but when anumber of elements (semiconductor light sources or sensors) areinterconnected for this purpose to form groups. This grouping can bothbe performed permanently, for example by hard-wiring, or else befashioned flexibly within the context of targeted control and selection.

A compact design of the multifunctional illumination device can beimplemented in a particularly advantageous way by selecting upstream ofthe individual semiconductor light sources optical systems in the formof a two-dimensional Cartesian oval, as also described in the patentapplication DE 102 49 819.9, which is not a prior publication. Theoptical systems are designed in this case to be as flat as possible suchthat the light entry opening of the optical system has an elongated,substantially rectangular shape. It is advantageous in this case whenthe optical system has perpendicular to the light entry surface acentral region whose projection into a two-dimensional plane correspondsto a cylindrical 2-dimensional Cartesian oval. A Cartesian oval is ageometrical surface that, as boundary surface of a refracting medium,collects the light emanating from a focal point in a second focal pointeven for large aperture angles. In order to make even better use oflight emanating from the semiconductor light source, the light exitsurface of the optical system, which is formed in the shape of aCartesian oval, can be combined with a parabolic reflector.

DETAILED DESCRIPTION OF THE INVENTION

The multifunctional illumination device can be fashioned in aparticularly advantageous and compact way aimed at efficiency byassigning at least individual optical systems a number of semiconductorlight sources or sensor elements. In such a case, one optical systemacts on the individual light sources and sensors in a different way suchthat these exhibit different emission characteristics and receptioncharacteristics. In practice, this can frequently be utilized extremelyadvantageously, for example by positioning a semiconductor light sourceat an optical system such that when functioning as a lower beam itilluminates the area right in front of a vehicle, while the sensor ispositioned at the optical system such that can detect signals fromregions further away in front of the vehicle. Such an arrangement isshown by way of example in a diagrammatic illustration of the figurerelating to this application. The figure shows the cross section of anoptical system (1) that is generally of flat design and at whose lightentry surface there are arranged, firstly, a semiconductor light source(2) and, secondly, a sensor element (3). The sensor element can be, forexample, a photodiode or a millimeter wavelength antenna (MMIC or SIMWICcomponent) implemented on a substrate. Owing to the optical propertiesof the optical system, the beam path and the light source (2) and thereceiving range of the sensor element (3) are separated from one anotherand directed toward different regions in the surroundings of themultifunctional illumination device; here, directly in front of thevehicle in the lower beam region, and for the purpose of determiningvisibility, for example, in remote regions.

Novel systems for measuring distance and/or determining visibility canbe implemented in conjunction with the multifunctional illuminationdevice according to the invention, it being possible in such systems, inparticular, to implement the front end (light source and sensor) in aparticularly compact fashion. Again, owing to the integration ofphotodiodes in the multifunctional illumination device it is possible tomeasure the ambient light precisely with the aid of that illuminatorwhich is intended to provide the light power required for compensatingweak ambient light.

In particular, systems for night vision improvement that operate on thebasis of active infrared or ultraviolet ambient illumination can beimplemented in a space-saving fashion and in a robust design in acompact unit.

Again, particularly given integration of millimeter wavelength antennas,the multifunctional illumination device is suitable for detectingobjects in the surroundings of the device using the radar principle.

1. A multifunctional illumination device, in particular for use in amotor vehicle, wherein the luminous means of the illumination device areformed by an arrangement of a multiplicity of semiconductor lightsources (2) grouped to form an array, sensor elements (3) are arrangedinstead of the semiconductor light sources (2) at individual positionsof this array, at least one semiconductor light source (2) and at leastone sensor (3) are selected from the multiplicity of semiconductor lightsources (2) and sensor elements (3) and are assigned to a common opticalsystem (1), the assignment with reference to the optical system (1) isperformed in such a way that the optical system (1) acts on thesemiconductor light source (2) and sensor (3) such that these havedifferent emission and/or reception characteristics, and perpendicularto the light entry surface the individual optical systems (1) have acentral region whose projection into a two-dimensional plane correspondsto a cylindrical 2-dimensional Cartesian oval.
 2. The multifunctionalillumination device as claimed in claim 1, wherein the semiconductorlight sources (2) emit light in different wavelength regions.
 3. Themultifunctional illumination device as claimed in claim 1, whereinoptical systems (1) assigned to the individual semiconductor lightsources (2) are designed as flat elements whose light entry opening havean elongated, substantially rectangular shape.
 4. The multifunctionalillumination device as claimed in claim 3, wherein the central region ofthe optical systems (1) is combined with a parabolic reflector. 5.(canceled)
 6. The multifunctional illumination device as claimed inclaim 1, wherein the illumination device comprises a means enabling theindividual semiconductor light sources (2) and the sensor elements (3)to be switched individually or in groups.
 7. The multifunctionalillumination device as claimed in claim 1, wherein the specific sensorelements (3) are assigned to specific semiconductor light sources (2),and a means is provided for operating the sensor elements (3) in afashion synchronized with the semiconductor light sources (2) assignedto them.
 8. The multifunctional illumination device as claimed in claim1, wherein the sensor elements (3) are photodiodes.
 9. Themultifunctional illumination device as claimed in claim 1, wherein thesensor elements (3) are antennas.
 10. The multifunctional illuminationdevice as claimed in claim 9, wherein the antennas (3) are connected toa transceiver unit.
 11. A method for operating a multifunctionalillumination device wherein the luminous means of the illuminationdevice are formed by an arrangement of a multiplicity of semiconductorlight sources grouped to form an array, sensor elements are arrangedinstead of the semiconductor light sources at individual positions ofthis array, at least one semiconductor light source (2) and at least onesensor (3) are selected from the multiplicity of semiconductor lightsources (2) and sensor elements (3) and are assigned to a common opticalsystem (1), the assignment with reference to the optical system (1) isperformed in such a way that the optical system (1) acts on thesemiconductor light source (2) and sensor (3) such that these havedifferent emission and/or reception characteristics, and perpendicularto the light entry surface the individual optical systems (1) have acentral region whose projection into a two-dimensional plane correspondsto a cylindrical 2-dimensional Cartesian oval, the method comprising:driving the sensor elements (3) and semiconductor light sources (2)independently individually or in groups.
 12. The method as claimed inclaim 11, wherein individual sensor elements (3) are operatedsynchronously with semiconductor light sources (3) assigned to them. 13.The method as in claim 11, wherein said multifunctional illuminationdevice is operated for the purpose of measuring distances and/ordetermining visibility.
 14. The method as in claim 11, wherein saidmultifunctional illumination device is operated for the purpose ofmeasuring the ambient light.
 15. The method as in claim 11, wherein saidmultifunctional illumination device is operated in a system forimproving night vision that operates on the basis of active infrared orultraviolet ambient illumination.
 16. The method as in claim 11, whereinsaid multifunctional illumination device is operated as avehicle-to-vehicle communication system in a motor vehicle.
 17. Themethod as in claim 11, wherein said multifunctional illumination deviceis operated for the purpose of detecting objects in the surroundings ofthe device using the radar principle.
 18. The multifunctionalillumination device as claimed in claim 2, wherein the semiconductorlight sources (2) emit light in both the visible wavelength region andthe infrared wavelength region.